Network Management. Raj Jain Raj Jain. Washington University in St. Louis

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Network Management Raj Jain Raj Jain Washington University in Saint Louis Saint Louis, MO 63130 Jain@wustl.

1 Network Management Raj Jain Raj Jain Washington University in Saint Louis Saint Louis, MO Audio/Video recordings of this lecture are available on-line at: 9-1

2 Overview What is Network Management and How? OSI Net Management Standards ASN.1 Management Information Base (MIB) SNMP: Protocol, Message formats SNMP V2 and SNMP V3 Note: This class lecture is based on Chapter 9 of the textbook (Kurose and Ross) and the figures provided by the authors. 9-2

3 What is Network Management? Traffic on Network = Data + Control + Management Data = Bytes/Messages sent by users Control = Bytes/messages added by the system to properly transfer the data (e.g., routing messages) Management = Optional messages to ensure that the network functions properly and to handle the issues arising from malfunction of any component If all components function properly, control is still required but management is optional. Examples: Detecting failures of an interface card at a host or a router Monitoring traffic to aid in resource deployment Intrusion Detection 9-3

4 Components of Network Management 1. Performance Management: Measure, report, analyze, and control traffic, messages 2. Fault Management: Detect, log, and respond to fault conditions 3. Configuration Management: Track and control which devices are on or off 4. Accounting Management: Monitor resource usage for records and billing 5. Security Management: Enforce policy for access control, authentication, and authorization 9-4

5 How is Network Managed? Management = Initialization, Monitoring, Control Manager, Agents, and Management Information Base (MIB) Network Management Station MIB Agent Network Agent MIB Agent MIB 9-5

6 Example of Network Management Management Server (Manager) Router (Agent) Router (Agent) Router (Agent) Agent Agent 9-6

7 OSI Net Management Standards Common Management Information Protocol (CMIP) Common Management Information Service (CMIS) CMIP is the management (application layer) protocol CMIS is the service interface to CMIP It was expected that OSI management standards will eventually be used in the Internet. So a tentative simple solution was developed for the time being: Simple Network Management Protocol (SNMP) SNMP is now used throughout. CMIP/CMIS is being replaced by SNMP. 9-7

8 Internet Management Framework 1. Structure of Management Information (SMI): Data definition language for objects ASN.1 was defined by ISO and is used in SNMP. 2. Management Information Base (MIB): Distributed network management data 3. SNMP protocol: Manager Managed object communication 4. Security, administration capabilities: Major addition in SNMPv3 9-8

9 ASN.1 Abstract Syntax Notation One Joint ISO and ITU-T standard, Original 1984, latest Used to specify protocol data structures X.400 electronic mail, X.500 and LDAP directory services, H.323 VOIP, SNMP, etc use ASN.1 Pre-Defined: 1=Boolean, 2=Integer, 3=Bit String, 4=Octet String, 5=Null, 6=Object Identifier, 9=Real Constructed: SEQUENCE (structure), SEQUENCE OF (lists), CHOICE,

10 SMI Base Data Types Data Type Description INTEGER ASN.1 32-bit integer between and Integer32 32-bit integer between and Unsigned32 Unsigned 32-bit integer between 0 and OCTET STRING ASN.1 byte string for binary or text up to 65,535 bytes long OBJECT ASN.1 format administratively assigned object identifier IDENTIFER IPaddress 32-bit Internet address in network-byte order Counter32 32-bit counter that increases from 0 to and wraps to 0 Counter64 64-bit counter Gauge32 32-bit integer that does not count above or below 0 TimeTicks Time interval measured in 1/100 th of a second Opaque Uninterpreted ASN.1 string (needed for backward compantibility) 9-10

11 ASN.1 Example AddressType ::= SEQUENCE { name OCTET STRING, number INTEGER, street OCTET STRING, city OCTET STRING, state OCTET STRING, zipcode INTEGER } 9-11

12 Encoding Rules ASN.1 only specifies the structure. Encoding rules indicate how to encode the structure in to bits on the wire. Examples: Basic Encoding Rules (BER), Packed Encoding Rules (PER), XML Encoding rules (XER), Distinguished Encoding Rules (DER),... In BER, everything is encoded as Tag-Length-Value. 9-12

13 BER Example John Miller, 126 Main Street, Big City, MO B 4A 6F 68 6E 20 4D 69 6C 6C Seq. Len Oct Str Len J o h n M i l l e r FE Int Len B 4D E Oct str 11 M a i n S t r e e t Oct Str Len B i g C i t y D 4F F Oct Str Len M O Int len Null 9-13

14 Management Information Base MIBs follow a fixed naming and structuring convention Structure of Management Information (SMI) These conventions were adopted from Common management Information Protocol (CMIP) designed by ISO All names are globally unique All nodes of the name tree are assigned numeric values by standards authorities iso.org.dod.internet.mgmt.mib.ip.ipinreceives Tables rows are referenced by appending the index All names are specified using a subset of Abstract Syntax Notation (ASN.1) ASN.1 specifies notation (that humans can read) and encoding (representation and ranges) 9-14

15 Global Naming Hierarchy ccitt(0) iso (1) joint-iso-ccitt (2) standard (0) iso9314 (9314) fddimib (1) org (3) dod (6) internet (1) directory (1) mgmt(2) experimental (3)private (4) system (1) interfaces (2) mib (1) UDP (7) fddi (8) transmission(10) fddimib (73) UDPInDatagrams (1) 9-15 fddi (15)

16 MIB Naming Example: UDP Module Object ID Name Type Comments UDPInDatagrams Counter32 total # datagrams delivered at this node UDPNoPorts Counter32 # underliverable datagrams no app at portl UDInErrors Counter32 # undeliverable datagrams all other reasons UDPOutDatagrams Counter32 # datagrams sent udptable SEQUENCE one entry for each port in use by app, gives port # and IP address 9-16

17 MIB Definition: Example ipaddrtable ::= SEQUENCE of ipaddrentry ipaddrentry ::= SEQUENCE { ipadentaddr ipaddress, ipadentifindex INTEGER, ipadentnetmask ipaddress, ipadentbcastaddr ipaddress, ipadentreasmmaxsize INTEGER ( ) } ipaddrentry {ipaddrtable 1} ipadentnetmask {ipaddrtable 3} 9-17

18 SNMP Based on Simple Gateway Management Protocol (SGMP) RFC 1028 Nov 1987 SNMP = Simply Not My Problem [Marshall Rose] Simple Network Management Protocol RFC 1058, April 1988 Only Five commands Command get-request get-next-request get-response set-request trap Meaning Fetch a value Fetch the next value (in a tree) Reply to a fetch operation Store a value An event 9-18

19 SNMP protocol Two ways to convey MIB info, commands: Managing Entity Managing Entity Request Response Trap Msg Agent data Managed device Request/response mode Agent data Managed device Trap mode 9-19

20 SNMPv2 PDU Types SNMPv2 PDU Sender- Description Type Receiver GetRequest Managerto-agent Get value of one or more MIB object instances GetNextRequest Managerto-agent Get value of next MIB object instance in list or table GetBulkRequest Managerto-agent Get values in large block of data, e.g., whole table InformRequest Managerto-manager Inform remote managing entity of MIB values SetRequest Managerto-agent Set value of one or more MIB object Response Agent-to- Manager GetRequest, GetNextRequest, GetBulkRequest,SetRequest or InformRequest SNMPv2 Trap Angent-to- Inform manager of exceptional 9-20

21 SNMP Message Formats 9-21

22 SNMPv1 Configuration Manager sends request to UDP port 161. Agents send traps to UDP port

23 SNMPv2 Improved security: authentication and integrity using Data Encryption Standard (DES) inform request Multiple manager coordination Locking mechanisms prevent multiple managers from writing at the same time get bulk Better table handling Confirmation option for Traps Agents can ensure that trap was received correctly. New Error codes: nosuchname, badvalue, readonly Reference: RFC 1441, April 1993 and more 9-23

24 SNMPv3 Security update of SNMPv2 Authentication: Message authentication code with a shared secret key Privacy: Encryption using a shared secret key Access Control: Each manager can have a different set of read/write permission for various component of MIB Ref: RFC 2570, April 1999 and more 9-24

25 SNMPv3 Engine SNMP Applications generate GetRequest, SetRequest,, commands SNMP Engine where SNMP version is determined, wrapped in a header containing version, message ID, size and then in a security wrapper. SNMP Application SNMP Engine Transport Network Datalink Physical 9-25 Dispatching Message Processing Timeliness Authentication Privacy Access Control

26 Summary Management = Initialization, Monitoring, and Control SNMP = Only 5 to 7 commands Standard MIBs defined for each object Uses ASN.1 encoding SNMPv2 fixed issues with bulk requests and simple security SNMPv3 added security 9-26

27 Try but do not submit Review Exercises Review Questions: R1 through R12 Problems P1 through P8 9-27

Simple Network Management Protocol. Slide Set 8

Simple Network Management Protocol Slide Set 8 Network Management Framework Internet network management framework MIB: management information base SMI: data definition language SNMP: protocol for network